The invention relates to a method for operating a water-bearing domestic appliance.
Modern water-bearing or water-conducting household appliances, such as e.g. dishwashers or washing machines, are provided with a water feed system by means of which a volume of water required for a specific program step can be supplied to the household appliance on the basis of an automatically executing program controller. Thus, in dishwashers, for example, various wash programs are used which typically include the program steps “pre-wash”, “clean”, “intermediate wash”, “rinse” and “dry”. In order to wash the items requiring to be washed a certain amount of washing solution (“wash liquor”) is required according to the particular program step, this amount being set via the water supply system.
Regular maintenance operations are necessary in water-bearing domestic appliances in order to ensure problem-free operation over a prolonged period of time. For example, the water supplied in modern dishwashers is softened by means of a special water softening device (ion exchanger) in order to avoid chalky deposits (“limescale”) in the water-conducting components and limescale residues on the items being washed. When water is routed through the ion exchanger, the Ca2+ ions responsible for the water hardness are replaced by Na+ ions, for example, as a result of which the water becomes softer. When the ion exchanger becomes fully loaded with Ca2+ ions, it is necessary to perform a regeneration, this being effected by using a regeneration salt by means of which the Ca2+ ions contained in the ion exchanger are replaced by Na+ ions, for example.
In the prior art such an automatically executing regeneration of the ion exchanger initiated by means of the program controller is performed following completion of a specific number of wash cycles preset ex works, the number varying as a function of a local water hardness requiring to be set manually by the user.
The factory presets known from the prior art do not take into account a characteristic deterioration in the exchanger performance of the ion exchanger with advancing lifetime of the appliance, with the result that a degradation of exchanger performance can occur already in the case of older appliances before the next regeneration of the ion exchanger is due.
In similar fashion a number of further maintenance operations are necessary in water-bearing domestic appliances, such as checking the circulation pump serving to circulate the wash liquor, for example, and cleaning or replacing a water filter in the feed system, which activities in the prior art are usually carried out after a period in the appliance lifetime has elapsed which is based on empirical values, without taking into account in this case an actual degree of wear to which the individual domestic appliance has been subjected, with the possible consequence that the corresponding maintenance activities may not be carried out until it is too late, at a time when losses in functional efficiency have already occurred.